1. Field of the Invention
The present invention relates to a method of manufacturing a thin film transistor substrate. More particularly, the present invention relates to a method of manufacturing a thin film transistor substrate using three masks.
2. Description of the Related Art
In general, a display apparatus displaying an image includes a substrate. The substrate includes a plurality of pixel areas defined thereon to display the image. Each pixel area includes a thin film transistor and a pixel electrode. In order to form the thin film transistor and the pixel electrode, a conductive layer is formed on the substrate and patterned.
The substrate includes various insulating layers formed on and under the thin film transistor or the pixel electrode. Patterning processes for conductive layers and the insulating layers are required to manufacture the substrate for the display apparatus. In the patterning processes, a photolithography process including an exposure and development is performed.
In general, the photolithography process is performed independently at each layer, and at least four photolithography processes are repeatedly performed to form the thin film transistor and the pixel electrode for a liquid crystal display. As the number of photolithography processes increases, the whole manufacturing process becomes complicated, thereby causing the increase in manufacturing cost.